Question

______ organisms were the first life forms to appear on earth.
a complex multi - cellular
b simple single - celled
c simple multi - cellular
d complex single - celled

Explanation:

The first life forms on Earth were the simplest possible organisms, as complex life evolved much later. Simple single-celled organisms (like bacteria) emerged first, before any multi-cellular or complex single-celled life.

Answer:

b. Simple single-celled